I have a major piece of evidence ok
so
context

as u might already know the Red String of Fate is used in East Asian culture to symbolise the connection between two destined lovers 

have you ever looked at Ja’far’s wrists and arms? 

he has red threads wrapped around his a p p e n d a g e s right?

And that red thread is connected to his daggers, Bararaq Sei, his connection to Sinbad (being his Household Vessel)

Sinbad who can see the path of fate & in addition saves Ja’far from meeting a terrible fate by literally taking fate into his own hands (more specifically, taking Ja’far’s fate into his own hands) thus intertwining their fates

do u see what i am sayin

The red cord wrapped around Ja’far’s arms is the Red String of Fate connecting him to Sinbad!

^^^^Good post op